The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it may be described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present technology.
Transmission components must be high strength and suitable for high torque capacities. Powder metal transmission components provide several technical benefits, and are becoming more attractive from manufacturing strategies and perspectives. The Ravigneaux planetary gearset is a double planetary gearset that is commonly used in various automatic transmission assemblies to efficiently achieve a variety of gear ratios. The Ravigneaux carrier structure includes two decks of gears that share a common carrier, but each mesh with a unique sun gear. A typical powder metal Ravigneaux carrier structure includes three pieces in order to accommodate the two decks of pinion gears, namely a cylindrical shell or drum, a support member, and a backing plate.
Generally, reducing the number of parts in any assembly reduces part management costs, as well as material costs. Specifically with respect to powder metal, the green components are fragile prior to sintering. Thus, a reduction in the number of separate powder metal components not only reduces part count, but also reduce part handling, which can reduce any risk of breakage, quality issues, or defects.
Accordingly, there remains a need for an improved powder metal carrier assembly that provides strength and ease of manufacture, with the ability to meet the high torque requirements needed for use in a transmission.